Perpetual calendar



FIG. 1 is a front elevational view of a perpetual calendar showing my new design;

FIG. 2 is a right side elevational view thereof, with the opposite side being a mirror image;

FIG. 3 is a rear elevational view thereof; and,

FIG. 4 is a top plan view thereof, with the bottom being a mirror image. 

The ornamental design of a perpetual calendar, as shown and described. 